Oracle TNS - can't connect through ODBC Administrator

my Oracle ODBC has stopped working today and i can't figure out why.

the error im getting when testing the con开发者_高级运维nection in ODBC Administrator is: connect failed because target host or object does not exist

getting the same error when trying to do a tnsping on it.

everything worked on friday, and no updates or anything has been done to the server.

what could it be?

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TNSPING and PING will go a long way.
If you see a line like

.. Attempting to connect to (ADDRESS=SomeServerOrIPAddress)(PORT=1521) ...

from TNSPING, try pinging the address yourself from the command prompt

PING SomeServerOrIPAddress

If you get a good reply from PING but not TNSPING it's now an issue for your DBA.
If PING doesn't work you need to look at network issues:
- Is the client actually connected to the network ?
- Name resolution if PING said it can't resolve the server name - Firewalls / Virus checkers blocking your traffic
- any number of other things